Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
OPERATING ACTIVITIES
Net income	$ 201,936	$ 185,445
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	36,590	25,462
Provision for credit loss expense	68,030	38,337
Gain on sale of investments	(54,790)	(12,937)
Net accretion of investment securities and assets	(43,286)	(35,272)
Net amortization on borrowings	406	273
Stock-based compensation expense	10,750	9,316
Gain on sale of premises and equipment, net of impairment	(33)	0
Gain on sale of foreclosed assets held for sale	(475)	(16)
Gain on sale of mortgage loans held for sale	(28,994)	(14,196)
Loss on sale of loans	0	4,451
Gain on sale of Visa, Inc. class B common stock	0	(42,860)
Gain on sale of other intangibles	(301)	0
Gain on sale of branches	(8,094)	0
Fair value write-down of closed branches	1,465	0
Deferred income taxes	2,920	10,933
Income from bank owned life insurance	(4,983)	(3,438)
Originations of mortgage loans held for sale	(851,356)	(499,178)
Proceeds from sale of mortgage loans held for sale	745,723	490,674
Changes in assets and liabilities:
Interest receivable	(15,601)	(679)
Lease right-of-use assets	8,147	(1,370)
Other assets	(7,009)	13,325
Accrued interest and other liabilities	35,549	10,881
Income taxes payable	(20,206)	18,722
Net cash provided by operating activities	76,388	197,873
INVESTING ACTIVITIES
Net collections (originations) of loans	243,826	(299,013)
Proceeds from sale of loans	32,742	104,587
Decrease in due from banks - time	493	395
Purchases of premises and equipment, net	(22,697)	(37,523)
Proceeds from sale of premises and equipment	123	0
Proceeds from sale of foreclosed assets held for sale	9,705	16,139
Proceeds from sale of available-for-sale securities	1,717,364	543,400
Proceeds from maturities of available-for-sale securities	2,218,259	412,006
Purchases of available-for-sale securities	(3,169,534)	(592,165)
Proceeds from maturities of held-to-maturity securities	10,520	29,179
Purchases of held-to-maturity securities	(16,997)	0
Proceeds from bank owned life insurance death benefits	1,425	1,310
Disposition of assets and liabilities held for sale	181,271	1,245
Purchase of Reliance Bancshares, Inc.	0	(37,017)
Net cash provided by investing activities	1,206,500	142,543
FINANCING ACTIVITIES
Net change in deposits	191,714	(156,010)
Repayments of subordinated debentures	(5,927)	0
Dividends paid on preferred stock	(39)	(326)
Dividends paid on common stock	(56,141)	(45,722)
Net change in other borrowed funds	45,170	(404,455)
Net change in federal funds purchased and securities sold under agreements to repurchase	163,549	6,598
Net shares cancelled under stock compensation plans	(3,355)	(3,301)
Shares issued under employee stock purchase plan	956	1,312
Retirement of preferred stock	0	(42,000)
Repurchases of common stock	(93,307)	0
Net cash provided by (used in) financing activities	242,620	(643,904)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	1,525,508	(303,488)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	996,623	833,458
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 2,522,131	$ 529,970